Using GROUP_CONCAT and STRING_AGG for String Aggregation in SQL

Using GROUP_CONCAT in MySQL & STRING_AGG in PostgreSQL

Write a SQL query to concatenate employee names by department, using GROUP_CONCAT in MySQL and STRING_AGG in PostgreSQL.

Solution:

-- MySQL
SELECT DepartmentID, GROUP_CONCAT(Name SEPARATOR ', ') AS EmployeeNames
FROM Employees
GROUP BY DepartmentID;

-- PostgreSQL
SELECT DepartmentID, STRING_AGG(Name, ', ') AS EmployeeNames
FROM Employees
GROUP BY DepartmentID;

Explanation:

• Purpose of the Query :
• The goal is to demonstrate how string aggregation differs between MySQL and PostgreSQL.
• Key Components :
• GROUP_CONCAT (MySQL): Concatenates values with a separator.
• STRING_AGG (PostgreSQL): Achieves the same result with different syntax.
• Why Compare String Aggregation?:
• String aggregation functions vary across platforms, impacting query portability.
• Understanding these differences ensures accurate results.
• Real-World Application :
• In reporting systems, concatenating names supports concise summaries.

Additional Notes:

• Use GROUP_CONCAT in MySQL and STRING_AGG in PostgreSQL.
• Test queries on all target platforms to ensure consistent results.
• Important Considerations:
• Handle null values to avoid unexpected results.

For more Practice: Solve these Related Problems:

• Write a SQL query to concatenate product names by category, using GROUP_CONCAT in MySQL and STRING_AGG in PostgreSQL.
• Write a SQL query to concatenate customer names by city, using GROUP_CONCAT in MySQL and STRING_AGG in PostgreSQL.
• Write a SQL query to concatenate order IDs by customer, using GROUP_CONCAT in MySQL and STRING_AGG in PostgreSQL.
• Write a SQL query to concatenate employee names by project, using GROUP_CONCAT in MySQL and STRING_AGG in PostgreSQL.

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